Uterine sarcoma is a disease in which malignant (cancer) cells form in the muscles of the uterus or other tissues that support the uterus.

The uterus is part of the female reproductive system. The uterus is the hollow, pear-shaped organ in the pelvis, where a fetus grows. The cervix is at the lower, narrow end of the uterus, and leads to the vagina. Uterine sarcoma is a very rare kind of cancer that forms in the uterine muscles or in tissues that support the uterus. Uterine sarcoma is different from cancer of the endometrium, a disease in which cancer cells start growing inside the lining of the uterus.